Integrated energy generating damper

ABSTRACT

A linear energy harvesting device that includes a housing and a piston that moves at least partially through the housing when it is compressed or extended from a rest position. When the piston moves, hydraulic fluid is pressurized and drives a hydraulic motor. The hydraulic motor drives an electric generator that produces electricity. Both the motor and generator are central to the device housing. Exemplary configurations are disclosed such as monotube, twin-tube, tri-tube and rotary based designs that each incorporates an integrated energy harvesting apparatus. By varying the electrical characteristics on an internal generator, the kinematic characteristics of to the energy harvesting apparatus can be dynamically altered. In another mode, the apparatus can be used as an actuator to create linear movement. Applications include vehicle suspension systems (to act as the primary damper component), railcar bogie dampers, or industrial applications such as machinery dampers and wave energy harvesters, and electro-hydraulic actuators.

BACKGROUND

1. Field

Aspects relate to damper systems and linear and rotary energy capturesystems that capture energy associated with relative motion.

2. Discussion of Related Art

A typical damper dissipates energy associated with motion. Lineardampers typically include a housing with a piston positioned inside thatis movable in both a compression stroke and an extension stroke. Anorifice is positioned in the piston. The motion of the piston causes aviscous fluid to pass through the orifice as the piston moves in orderto dampen motion.

Primary damper technologies have been in use for decades and can besplit into two main groups: monotube dampers and twin-tube dampers(although certain tri-tube dampers have been produced, these are usedfor specialized adaptive dampers and are not in widespread production).Monotube dampers feature a hydraulic ram with orifices in the pistonhead and a gas-filled reservoir inside the main fluid chamber. Twin-tubedampers feature two concentric tubes with an inner tube filled withhydraulic fluid and the external tube containing fluid and gas or someother compressible medium.

SUMMARY

Conventional dampers, when providing dampening, dissipate a significantamount of energy as heat. The inventors have appreciated thatimprovements on conventional damper technologies can provide energyrecovery and dynamic damping control capabilities [while sharing aconsiderable number of parts with conventional low-cost dampertechnologies].

Aspects relate to an energy-generating device that captures energyassociated with relative motion, whilst providing damping to movement—ina compact, self-contained apparatus, offering the ability to be a directreplacement for non-energy harvesting dampers.

According to one aspect, an energy-generating damper contains a pistonhead with an integrated hydraulic motor (which, in some embodiments, maybe a positive displacement motor) that includes a first port and asecond port. The first port is in fluid communication with a compressionvolume and a second port is in fluid communication with an extensionvolume. The piston head further contains an electric generator that isdirectly coupled to the hydraulic motor. The fluid flow causes thehydraulic motor to rotate and hence rotates the electric generator whichproduces electricity. According to another aspect, an energy-generatingdamper comprises a housing that includes a compression volume and anextension volume. A piston head that contains an integrated hydraulicmotor with a first port and a second port is disposed in the housing.The first port is in fluid communication with the compression volume andthe second port is in fluid communication with the extension volume. Thepiston head further to includes an electric generator that that isdirectly coupled to the hydraulic motor, so that rotation of thehydraulic motor causes rotation of the electric generator which produceselectricity as it rotates. In a first mode, the piston moves through atleast a portion of a jounce (compression) stroke which causes fluid toflow from the compression volume to the first port, rotating thehydraulic motor and generator, producing electricity. In a second mode,the piston moves at least partially through a rebound (extension) strokewhich causes fluid to flow from the extension volume to the second port,counter-rotating the hydraulic motor and generator, producingelectricity. A fluid reservoir is in fluid communication with either thecompression or extension volume. According to another aspect, anenergy-generating damper comprises an inner housing that includes acompression volume and an extension volume. A piston is disposed in theinner housing. In a first mode, the piston moves through at least aportion of a jounce stroke to displace hydraulic fluid from thecompression volume. In a second mode, the piston moves at leastpartially through a rebound stroke to displace hydraulic fluid from theextension volume. An outer tube is concentric with the inner tubecontaining the compression and extension volumes. The outer tubecontains the low-pressure volume. The low-pressure volume contains acompressible medium. The piston head disposed in the inner housingcontains an integrated hydraulic motor that includes a first port and asecond port. The first port is in fluid communication with thecompression volume and the second port is in fluid communication withthe extension volume. The piston rod is hollow and contains a shaft thatconnects the hydraulic motor on the piston head with an electricgenerator on the other end of the piston rod. Rotation of the hydraulicmotor causes rotation of the electric generator. Damping is provided bythe electric generator, through the shaft inside the piston-rod, to thehydraulic motor, in order to restrict fluid flow between the compressionvolume and the extension volume. One or more valves restrict flow intoand out of the low-pressure volume such that during jounce fluid flowsfrom the compression volume to the low-pressure volume, and then intothe extension volume, the compressible medium in the low pressure volumecompressing to accept the rod volume. During rebound, fluid flows fromthe low-pressure volume to the compression volume the compressiblemedium expanding to replace piston rod volume.

According to another aspect, an energy-generating damper contains a basevalve at the opposite end of the damper from the fixed rod end. The basevalve comprises of a hydraulic motor that includes a first port and asecond port. The hydraulic motor is coupled with an to electric motor.Rotation of the hydraulic motor causes rotation of the electricgenerator. The energy-generating damper further includes two concentrictubes with an inner housing that includes a compression volume and anextension volume. A piston is disposed in the inner housing. In a firstmode, the piston moves through at least a portion of a jounce stroke todisplace hydraulic fluid from the compression volume. In a second mode,the piston moves at least partially through a rebound stroke to displacehydraulic fluid from the extension volume. An outer tube is concentricwith the inner tube containing the compression and extension volumes.The outer tube contains the low-pressure volume. The low-pressure volumecontains a compressible medium. The first port of the hydraulic motor isin fluid communication with, either directly or through valving, theextension volume and the second port of the hydraulic motor is in fluidcommunication with, either directly or through valving, the low pressurevolume containing the compressible medium.

According to another aspect, an energy-generating damper comprises aninner housing that includes a compression volume and an extensionvolume. A piston is disposed in the inner housing. In a first mode, thepiston moves through at least a portion of a jounce stroke to displacehydraulic fluid from the compression volume. In a second mode, thepiston moves at least partially through a rebound stroke to displacehydraulic fluid from the extension volume. A second tube is concentricto and outside of the inner tube containing the compression andextension volumes. The space between the second tube and the inner tubecontains the high-pressure volume. A third tube is concentric to andoutside of the second tube. The space between the third tube and thesecond tube contains the low-pressure volume. The high-pressure andlow-pressure volumes may also be configured as being between the thirdtube and second tube, and the second tube and inner tube, respectively.The low-pressure volume contains a compressible medium. A hydraulicmotor that includes a first port and a second port is connected. Thefirst port is in fluid communication with the high-pressure volume andthe second port is in fluid communication with the low-pressure volume.One or more valves restrict and/or direct flow such that during jounce,the compression volume is connected to the high-pressure volume and theextension volume is connected to the low-pressure volume, and such thatduring rebound, the compression volume is connected to the low-pressurevolume and the extension volume is connected to the high-pressurevolume. Therefore in this aspect, flow through the hydraulic motor isunidirectional and spins during both jounce stroke and rebound strokemodes. The hydraulic motor is coupled with an electric motor. Rotationof the hydraulic motor causes to rotation of the electric generator.

According to another aspect, an energy-generating damper comprises aninner housing that includes a compression volume and an extensionvolume. A piston is disposed in the inner housing. In a first mode, thepiston moves through at least a portion of a jounce (compression) stroketo displace hydraulic fluid from the compression volume. In a secondmode, the piston moves at least partially through a rebound (extension)stroke to displace hydraulic fluid from the extension volume. Ahydraulic motor is connected to a shaft that connects to an electricgenerator that produces electricity when its shaft spins. The hydraulicmotor has a first port that connects to the compression volume and asecond port that is in fluid communication with the extension volume. Inthis regard, in one embodiment, the second port is directly connected tothe extension volume, for example, as in the integrated piston head orthe hydraulic motor piston head and piston rod opposed electricgenerator embodiments. In another embodiment, the second port isconnected via the outer tube, for example, as in the base valveconfiguration. The hydraulic motor and the electric generator arecoupled such that rotation of one causes rotation of the other. An outertube is concentric with the inner tube containing the compression andextension volumes. The outer tube contains an outer volume that is influid communication with the extension volume. Both the extension volume(via the outer volume) and the compression volume are in fluidcommunication with a valve block that operates such that an accumulatoralso attached to the valve block is in fluid communication with thelower pressure volume, either the compression volume or the extensionvolume.

According to another aspect, an energy-generating damper comprises ahousing that includes a compression volume and an extension volume. Apiston is disposed in the housing. In a first mode, the piston movesthrough at least a portion of a jounce (compression) stroke to displacehydraulic fluid from the compression volume. In a second mode, thepiston moves at least partially through a rebound (extension) stroke todisplace hydraulic fluid from the extension volume. The piston headcontains an integrated hydraulic motor that includes a first port and asecond port. The first port is in fluid communication with thecompression volume and the second port is in fluid communication withthe extension volume. The piston head further contains an electricgenerator that produces electricity when its shaft spins. Thepiston-head-mounted hydraulic motor and electric generator are coupledsuch that rotation of one causes rotation of the other. The piston rodis double ended, with a rod section on each side of the piston head,each going through the compression and extension volumes, respectively,and to exiting the housing from opposite sides.

According to another aspect, an energy-generating damper comprises anintegrated motor and generator coupled to a rotary damper. Theintegrated motor-generator comprises of a hydraulic motor that includesa first port and a second port. The hydraulic motor is coupled with anelectric motor. Rotation of the hydraulic motor causes rotation of theelectric generator. The energy-generating rotary damper further containsan input lever that is connected to a first volume(s) and a secondvolume(s). In first mode the input lever rotates through at least aportion of a stroke to displace fluid from the first volume. In secondmode the input lever rotates through at least a portion of the stroke todisplace fluid from the second volume. The first port of the hydraulicmotor is in fluid communication with the first volume and the secondport in the hydraulic motor is in fluid communication with the secondvolume.

According to another aspect, an energy-generating actuator contains abase valve at the opposite end of the piston rod. The base valvecomprises of a hydraulic motor that includes a first port and a secondport. The hydraulic motor is coupled with an electric motor. Rotation ofthe hydraulic motor causes rotation of the electric generator. Theenergy-generating actuator further contains two concentric tubes with aninner housing that includes a compression volume and an extensionvolume. A piston is disposed in the inner housing. In a first mode, thepiston moves through at least a portion of a compression stroke topressurize hydraulic fluid in the compression volume. In a second mode,the piston moves at least partially through an extension stroke topressurize hydraulic fluid in the extension volume. An outer tube isconcentric with the inner tube containing the compression and extensionvolumes. The outer tube contains the low-pressure volume and is in fluidconnection with the extension volume. The low-pressure volume contains acompressible medium. The first port of the hydraulic motor is in fluidcommunication with, either directly or through valving, the compressionvolume and the second port of the hydraulic motor is in fluidcommunication with, either directly or through valving, the low pressurevolume containing the compressible medium.

According to another aspect, an energy-generating actuator contains abase valve at the opposite end of the piston rod. The base valvecomprises of a hydraulic motor that includes a first port and a secondport. The hydraulic motor is coupled with an electric motor. The basevalve is connected to the actuator by a rectifying hydraulic circuit sothe direction of rotation of the hydraulic unit remains constantregardless of the direction of stroke of the actuator.

According to another aspect, the energy-generating dampers described inthe previous to paragraphs may include one or more directional and orfluid restrictive valves that provide fluid communication between thecompression volume and the extension volume to bypass fluid around or torestrict fluid through the hydraulic motor.

According to another aspect, the energy-generating dampers described inthe previous paragraphs are used with a controller that recoversgenerated energy and controls the kinematic characteristic on theenergy-generating damper. The controller in one aspect is wholly poweredby the energy-generating damper.

According to another aspect, the energy-generating dampers described inthe previous paragraphs are used with a spring assembly to force thepiston rod into an extended state. According to another aspect, theenergy-generating dampers described in the previous paragraphs are usedwith a spring assembly to force the piston rod into a compressed state.

BRIEF DESCRIPTION OF DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is an embodiment of an integrated piston head (IPH) that includesa hydraulic motor and electric generator.

FIGS. 2, 2A and 2B show another embodiment of an alternate integratedpiston head that includes a hydraulic motor and electric generator.

FIGS. 3, 3A, 3B and 3C show another embodiment of an integrated pistonhead that includes an integrated hydraulic motor and electric generator

FIGS. 4 and 4A, show an embodiment of a mono-tube damper including anIPH

FIG. 5 is an integrated energy-recovering twin-tube damper embodimentwith piston rod opposed hydraulic motor and electric generator.

FIG. 6 is an embodiment of integrated energy-recovering twin-tube damperwith a hydraulic motor electric motor/generator side valve.

FIG. 7 is an embodiment of an integrated energy-recovering tri-tubedamper with a hydraulic motor electric motor/generator side valve basevalve.

FIG. 8 is a twin tube IPH embodiment, schematically showing theaccumulator connected to the low pressure volume.

FIG. 9 is a monotube integrated piston head embodiment that utilizes athrough-shaft design.

FIG. 10 is an integrated energy-recovering rotary embodiment with anexternal integrated hydraulic motor.

FIGS. 11 and 11A, show an embodiment of an integrated energy-recoveringelectro-hydraulic actuator.

FIG. 12 is an embodiment of an energy harvesting actuator that willgenerate a constant direction of rotation of the motor/generatorregardless of the direction of stroke of the actuator.

FIGS. 13 and 13A show an embodiment of an integrated hydraulicpump/motor and electric motor/generator.

FIGS. 14 and 14A show an embodiment of an integrated energy-recoveringtri-tube damper with a hydraulic motor electric motor/generator sidevalve and base valve.

FIG. 15 shows an embodiment of an integrated energy-recovering tri-tubedamper with a hydraulic motor electric motor/generator and controlledhydraulic valves.

DETAILED DESCRIPTION

Some aspects of the system relate to an integrated energy generator thatis capable of harnessing energy from high force but relatively lowvelocity movement, without the need for external fluid circuits whichtypically lower system efficiency, and introduce durability problems andadded manufacturing costs. Several embodiments utilize traditionaldamper configurations and components, with improvements focused onintegration of energy harvesting componentry and valving on the pistonhead and elsewhere in the housing. While “damper” is used in referenceto the system, it should be noted that the invention is not limited tooscillatory systems nor is it merely an energy-extracting device, as itcan be actuated as well. Embodiments of the described integrated energygenerator may include a housing and a piston that moves at leastpartially through a compression stroke when compressed. The piston mayadditionally move at least partially through an extension stroke whenextended (i.e., the piston may be double-acting). When the piston moves,hydraulic fluid is pressurized and moved to drive a hydraulic motor. Thehydraulic motor drives an electric generator that produces electricity.

According to one aspect, a coupled hydraulic motor and electricgenerator are integrated into the piston head of a conventional damper.A traditional monotube configuration may be used with a gas-filledaccumulator at the base of the damper. Alternatively, a twin tube designto with a selectively-valved accumulator configuration may be used withthe integrated piston head. In another illustrative embodiment, theintegrated piston head can be used with a double through-shaft damperdesign. However, use of the integrated piston head is not limited tothese illustrative embodiments.

According to another aspect, a hydraulic motor is integrated into thepiston head of a damper. The hydraulic motor has a shaft that extendsthrough the piston rod to an electric generator on the opposing side ofthe piston rod. In this embodiment, the damper is otherwise configuredsimilar to a traditional monotube. Alternatively, a twin-tubeconfiguration with a compression bypass may be employed with thishydraulic motor and electric motor/generator configuration. In anotherillustrative embodiment, the opposed motor/generator system can beemployed in a twin-tube design with a selectively-valved accumulator.However, use of the opposed hydraulic motor electric motor/generatorsystem is not limited to these illustrative embodiments.

According to another aspect, a hydraulic motor and electric generatorare integrated into the base valve of a damper. In one embodiment, atri-tube rectified system is employed using check valves, a low pressurevolume, and a high pressure volume. In another embodiment, a twin-tubedesign with an outer volume in communication with the extension volumemay be used with the integrated base valve along with aselectively-valved accumulator. However, use of the base valve system isnot limited to these illustrative embodiments.

Additional aspects relate to dynamically changing the kinematiccharacteristic of the energy generating damper. A control may be used tocontrol the magnitude of force on the piston of the damper to desiredlevels. By way of example, according to one embodiment, a response canbe controlled to mimic the force/velocity response (i.e., damping) of aconventional automotive damper, or in another example, one embodimentmay include a response that can be controlled to maximize harvestedenergy from an ocean wave input. Some aspects relate to the controllerpowering itself from the energy generated by the energy generatingdamper. This may allow for wireless semi-active control or fully-activecontrol.

Other aspects relate to energy generating dampers being assembled intothe suspension system of a vehicle. The energy generating dampers mayprovide a primary source of damping in the suspension system. However,the invention is not limited in this regard and other applications maybe utilized. For example, other aspects relate to energy generatingdampers being assembled into an industrial energy harvesting platform,such as an ocean swell energy harvesting system.

Turn now to the figures, and initially FIG. 1, which shows an embodimentof an integrated piston head that includes a hydraulic motor and anelectric generator. The integrated piston head 1 is disposed in ahydraulic cylinder with fluid both above and below the piston head. Whenfluid is pressurized above the piston head (with respect to fluidbelow), fluid flows into one or more inlet/outlet ports 2 above thepiston head. In the embodiment of FIG. 1, a positive displacementgerotor 3 is utilized as a hydraulic motor, although the presentinvention(s) is not limited in this regard. When fluid flows through theinlet/outlet 2, a pressure differential forces the gerotor mechanism 3to spin in its offset pocket. The gerotor motor 3 is drivingly connectedto the generator shaft 8, which in turn is drivingly connected to anelectric generator 5 immersed in the hydraulic fluid such that rotationof the hydraulic motor rotates the electric generator, and vice versa.Fluid flows from the inlet/outlet 2 through the hydraulic motor 3 andout the inlet/outlet port (or ports) 4 below the piston head. This spinsthe shaft 8, which spins the generator 5, which produces electricity.Electricity is carried via wires that are routed outside the piston headand damper housing through a hollow piston rod 6. A seal on the outerrim 7 of the piston head prevents fluid from bypassing the inlet/outletports by going around the piston head. When fluid is pressured below thepiston head, fluid passes into the inlet/outlet port (or ports) 4 belowthe piston head, through the hydraulic motor, and out the inlet/outletport (or ports) 2 above the piston head.

The generator shaft 8 is supported at either end by bearings 9 and theshaft 8 supports the inner gerotor element 10 and the rotor 11 of theelectrical generator 5. The outer gerotor element 12 is supported by ajournal bearing 13. A cover plate 14 axially locates the gerotor 3 inits pocket in the piston head. Shadow ports 15 may exist in both thepiston head and the cover plate so as to keep the gerotor assembly inhydraulic axial balance.

FIG. 2 shows an embodiment of an alternate integrated piston head tothat as shown in FIG. 1. In this embodiment, a positive displacementgerotor 16 is utilized as a hydraulic motor and differs from theembodiment shown in FIG. 1 in the fact that the outer element 17 of thegerotor motor 16 is drivingly connected to the generator 18 via thegenerator shaft 19, and the inner element 36 of the gerotor motor 16 isfree to rotate on an eccentric shaft 20. This arrangement allows theouter larger diameter element of the gerotor to share a common lowfriction bearing (such as a deep groove ball bearing or similar) withthat of the generator shaft to and the smaller inner diameter of theinner element to run directly on its shaft.

In the application of a damper, the piston velocity, and hence thegerotor motor velocity, is continually accelerating/decelerating in onedirection then stopping and then accelerating/decelerating in theopposite direction. Without being bound by theory, as the gerotor speedslows, any hydrodynamic lift generated on the plain bearing of thegerotor is lost, and higher friction on this bearing is applied. Thelarger the diameter of the this bearing the more torque is lost throughthis increased friction, and in the application when the gerotor is usedas a motor, this torque loss may equal, or even be greater than, thetorque generated by the motor itself, potentially causing the motor tostall. Even when there is sufficient speed at this plain bearinginterface to generate hydrodynamic lift, and hence cause a significantreduction in friction, again without being bound by theory, energy lostat this interface is proportional to the diameter to the power of 4,therefore it may be desirable to keep the plain bearing diameter assmall as possible in order to reduce energy losses. Utilizing the aboveunique bearing arrangement, the larger outer element is now supported bya low friction rolling element bearing that is also shared with thegenerator shaft, and the plain bearing interface is located on the smalldiameter of the inner element, offering the potential benefit of lowinitial startup torque and lower high speed power losses. Although lowfriction bearings are more expensive than plain hydrodynamic bearings,the fact the outer gerotor element shares the same low friction bearingas the generator shaft may mitigate any increase in cost.

By placing the low friction bearing over, or near, the axial centerlineof the outer gerotor element, all, or nearly all, of the radial loadgenerated by the outer gerotor element is passed to the low frictionbearing; this may enable the use of a low cost plain bearing on theopposite end of the generator shaft. As shown in FIG. 2, the diameter ofthis plain bearing 34 can be reduced to a size significantly smallerthan that of the outer gerotor element diameter to reduce its frictionalloss.

In the embodiment shown in FIG. 2 the integrated piston head 21 isdisposed in a hydraulic cylinder with fluid both above and below thepiston head. When fluid is pressurized above the piston head (withrespect to fluid below), fluid flows into one or more inlet/outlet ports22 in the piston head 21, along flow path 23. When fluid flows throughthe inlet/outlet 22, a pressure differential forces the gerotor 16 tospin on the offset journal 24 of the gerotor shaft 20. The outer element17 of the gerotor motor is drivingly connected to the generator shaft19, which in turn is drivingly connected to an electric generator 18,(which is immersed in the to hydraulic fluid) such that rotation of thehydraulic motor rotates the electric generator, and vice versa. Fluidflows from the inlet/outlet 22 through the hydraulic motor 16 andthrough the inlet/outlet port (or ports) 25 in the gerotor shaft andthrough the passages 26 in the generator can 27 to below the piston headas shown by flow path arrow 28. This fluid flow spins the gerotor whichin turn spins the generator shaft 19, which spins the generator 18,which produces electricity. In this embodiment, electricity istransmitted via wires 29 that are routed outside of the piston head anddamper housing, through a hollow piston rod 30 that is connected to thegenerator can 27, via a high pressure hydraulic seal 31. A seal 32 onthe outer rim of the piston head prevents fluid from bypassing theinlet/outlet ports by going around the piston head. When fluid ispressured below the piston head, fluid passes into the generator can 27via the passages 26 and into the inlet/outlet port 25 in the gerotorshaft 20, through the hydraulic motor, and out the inlet/outlet port (orports) 22 in the piston head.

The generator shaft 19 is supported at either end by bearings 33 and 34with the shaft 19 supporting the outer gerotor element 17 and the rotor35 of the electrical generator 18. The inner gerotor element 36 issupported via a journal bearing 24 on the gerotor shaft 20. The gerotorshaft also acts as a cover plate to axially locate the gerotor 16between the gerotor shaft and the piston head 21. Shadow ports 37 and 38in both the piston head and the gerotor shaft may be provided so as tokeep the gerotor assembly in hydraulic axial balance.

As shown in FIG. 2A, the port 25 in the gerotor shaft is open to thepressure in the generator can 27 and there is no outer sealing landaround this port. Since there is pressure differential between the fluidin port 25 and the generator can 27 an outer sealing land is notnecessary, and providing the gerotor with a reduced land contact mayreduce the friction drag between the gerotor and the sealing face of thegerotor shaft. The opposing shadow port 37 that exists in the pistonhead is also open to the pressure in the generator can 27 and also hasno outer sealing land around this shadow port. This not only helps keepthe gerotor in axial hydraulic pressure balance, but it also means thatas the fluid flows from the gerotor can into and out of the port 25, itwill also flow via the shadow port 37. As the fluid flows into and outof the shadow port 37, it must pass through the rolling elements of thelow friction bearing 33, thereby keeping the bearing running in acontinually refreshed supply of fluid and minimizing any localizedheating of the fluid due to friction losses.

As shown in FIG. 2B, the outer gerotor element 17 is drivingly connectedto the generator shaft via drive pins 39 that are secured into the outerelement. These pins are to connected to the generator shaft via slots 40that are disposed around the outer diameter of the generator shaft. Inone embodiment these pins are of the split spring type and not onlycarry the driving torque from the gerotor to the generator shaft but actas small shock arrestors, absorbing the shock loads that are placed inthe gerotor from the high frequency motion of the damper.

The generator shaft has passages 41 that allow the flow from the portsin the gerotor shaft to pass through the generator shaft into thegenerator can 27 and from there into the volume below the piston head.

Referring again to FIG. 2, the generator shaft contains a check valve 42that allows for a free flow from the piston head through the gerotor,through the shadow port of the generator shaft, through the passages inthe gerotor shaft into the generator can and from there into the volumebelow the piston head, by-passing the gerotor so that reduced damping(and reduced energy recovery) is achieved in the compression stroke. Thecheck valve is actuated by a spring 43; the preload on the spring can beadjusted so that the compression damping can be varied from a minimumvalue to a maximum value, whereby maximum compression damping isachieved, to suit different applications. The check valve will not allowflow to by-pass the gerotor on extension stroke so that full extensiondamping (and energy recovery) may be achieved.

A blow-off valve 44, as shown in FIG. 2, may be employed to limit themaximum pressure in the generator can and hence the maximum pressurethat exists on the bottom side of the integrated piston head (IPH).Pressure that exists in the generator can acts on a sealing washer 45via passages 46. The sealing washer is held against the sealing face onthe piston head by springs 47, blocking flow from the passages 46.Pressure acting over the area of the passages 46 generates a force tounseat the sealing washer, and once the force from the pressure in thegenerator can acting on the sealing washer overcomes the spring forcefrom the springs 47, the sealing washer unseats and allows flow from thegenerator can and hence the underside of the IPH, to the top side of theIPH, via slots 48 in the piston head (shown in FIG. 2A), by-passing thegerotor. The spring force and the number of passages acting upon thesealing washer can be varied to change the pressure at which theblow-off valve opens, to suit different applications.

The blow-off valve is used to limit the pressure differential thatexists across the gerotor under high extension strokes, so as to notonly limit the maximum extension damping force, but to also limit themaximum speed of the gerotor. This will keep the gerotor bearings andgenerator speeds to reasonable limits under high extension forces,thereby increasing the to durability of the IPH.

FIGS. 3, 3A, 3B and 3C show an embodiment of an IntegratedMotor/generator Unit (IMGU) that incorporates the features of theembodiment shown in FIG. 2 but in a more compact unit with a reducednumber of components. This embodiment can be used either in an IPHarrangement, as shown in FIG. 4A, or as an individual ‘valve’ that canbe incorporated in a damper or actuator as will be discussed below withrespect to FIG. 6. As in the previous embodiments, the IMGU may be usedas a generator or as hydraulic power source for elector-hydraulicactuators.

In this embodiment, and as in the embodiment shown in FIG. 2, the outerelement of the gerotor motor is drivingly connected to the generator 50in a similar manner as shown in the embodiment shown in FIG. 2, theinner element 51 of the gerotor motor is free to rotate on an eccentricshaft 52. This arrangement allows the outer element of the gerotor toshare common low friction bearings 53 with that of the generator shaft54 and the smaller inner diameter of the inner gerotor element to rundirectly on the eccentric shaft 52, and offers the efficiency and costbenefits as outlined in the embodiment shown in FIG. 2. In theembodiment shown in FIG. 3, the generator 50 is now placed concentricand co-planar with the gerotor motor 55, as opposed to concentric andadjacent as shown in FIG. 2. This arrangement not only reduces thelength and weight of the overall package it also reduces the number ofcomponents, thereby reducing cost whilst increasing durability. Magnets56 of the generator are drivingly connected (via bonding or othersuitable means) directly to the generator shaft 54 (as shown in FIG.3B), or can be connected directly to the outer gerotor element 49,thereby eliminating a separate rotor component. Two low frictionbearings 53 that support the generator shaft equally share the radialload from the outer gerotor element. As two bearings now equally sharethis load, substantial increase bearing life may be obtained, increasingthe durability of the IMGU. In the embodiment shown, the outer bearingraces 57 of the low friction bearings are formed directly into thegenerator shaft, eliminating the additional component of the outer race,whilst reducing the mass of the IMGU and the rotating inertia of thegenerator rotating assembly.

Gerotor caps 58 are positioned on either side of the gerotor elementsand contain a first flow port 59 and a second flow port 60; these portsmay be full flow or shadow ports as required by the application, and aresuch that the gerotor assembly is placed in axial hydraulic balance. Theport configuration can be symmetrical about both the vertical andhorizontal centerlines. The gerotor caps are connected and secured tothe IMGU end caps 61. Flow passages 62 and 63 to contained in the IMGUend caps connect to the first and second flow ports in the gerotor caps,so that as fluid flows from the one port to the other, rotation of thegerotor occurs.

By incorporating a symmetric layout of the porting arrangement, it ispossible for the flow path in and out of the hydraulic unit to be on thesame side on the IMGU or on opposite sides, thereby increasing theflexibility of use for different applications. This symmetrical partconfiguration also allows for additional valves and connections, such asby-pass valves pressure relief valves, accumulators etc. to bepositioned opposite the first and second flow ports, allowing for flowto occur through the gerotor as well as around the gerotor (i.e. to andfrom the first and second ports), offering a parallel flow path to thehydraulic unit. Again this may offer favorable packing configurations.

By positioning the gerotor motor 55 coplanar with the generator, flow inand out of the hydraulic unit via the first and second ports now occursthrough the center of the generator, as opposed to around or adjacent tothe generator, as shown in the embodiments of FIG. 1 and FIG. 2. Thisshortens and simplifies the flow paths, reducing viscous losses, therebyincreasing the efficiency of the unit.

Additional valves, such as pressure relief valves, by-pass valves, loadholding valves etc. can be incorporated into the gerotor caps and or theIMGU end caps (or even external to the IMGU end caps) to provideadditional functionality, both as a generator and as an actuator.

The inner races 64 of the low friction bearings are formed directly intothe gerotor caps (or into the IMGU end caps) and are axially retainedbetween the gerotor cap and the IMGU end cap. This further reduces theparts count by eliminating the need for a separate bearing inner race.In the embodiment shown the low friction bearings are of the cylindricalroller type, of course the bearing arrangement shown can be easilychanged to incorporate other types of low friction bearings, or evenplain bearings, as the application warrants, as the particularapplication is not limited in this regard.

In the embodiment shown in FIG. 3, the eccentric shaft 52 is heldstationary to the gerotor caps and the inner gerotor element rotatesrelative to the shaft supported by a plain journal bearing 65. Theeccentric shaft is used to connect and locate the gerotor caps and theIMGU end caps, and the IMGU assembly is secured via a threadedconnection 66, or other arrangement such as swaging and welding.Shoulders 67 on the eccentric shaft ensure an accurate spacing betweenthe gerotor caps is achieved, so that the correct axial clearance ismaintained between the gerotor and the end caps, for proper andefficient operation of the gerotor.

The stator 68 of the generator is drivingly connected to the outersleeve 69 (via bonding or other suitable arrangement), and the outersleeve is sandwiched between the two IMGU end caps so that the stator isheld concentric and in correct axial location with the generator shaft.A timing feature between the two IMGU end caps and the outer sleeveradially locates the IMGU end caps with respect to each other, to ensurecorrect timing of the flow ports and positioning of the eccentric shaft52.

Because of the compact nature of the Integrated Motor/generator Unit asshown in this embodiment, it is possible for the IMGU to be used as acartridge type regenerative valve, whereby the unit is placed in amachined bore or pocket of a device so that flow ports are aligned andsealed against the first and second ports of the IMGU. Flow can then becontrolled in a hydraulic circuit by controlling the back EMF of thegenerator, or the IMGU can act as a hydraulic power source by supplyingelectrical power to the generator to spin the hydraulic unit so that itacts as a pump. Possible uses of this kind of valve could be as apressure regulator or relief valve for larger hydraulic circuits.Normally, hydraulic valves with controllable orifices are used forpressure regulation in hydraulic circuits, and as such energy is wastedby throttling flow across these orifices. By incorporating the IMGU as aregenerative pressure control valve this energy can now be captured.

Other applications include variable hydraulic power sources, such as forengine or transmission lubrication pumps. Ordinarily these pumps are offixed displacement and driven at a certain shaft speed. These pumps aresized so as to meet the maximum expected flow demand at any given shaftspeed, and as such these pumps supply more flow than is normallyrequired, and energy is wasted through the use of flow control valves.Because of the compact size and cylindrical shape of the IMGU, it can beused to replace these pumps as a simple cartridge unit inserted into amachined cavity in the engine, transmission etc. or as an externallymounted unit. Because of the variable speed control and hence flowcontrol capability of the IMGU, the output of the pump can be preciselymatched to the demand at all times, thereby reducing the energyconsumption in these applications.

FIGS. 4 and 4A shows an embodiment of a monotube damper 10 that utilizesthe integrated piston head 1 of FIG. 2 and FIG. 3 respectively, however,the IPH could also be of the configuration as shown in FIG. 1. Here, theintegrated piston head 71 is disposed in a housing that includes acompression volume 73 and an extension volume 74. Additionally, afloating to piston 75 seals a gas-filled accumulator 76 and maintainspressure on the fluid inside the housing. When the piston rod 30undergoes jounce, fluid flows from the compression volume 73, throughthe integrated piston head 71, and into the extension volume 74. Duringthe jounce stroke, the floating piston 75 moves to compress the gas inorder to compensate for the volume of the piston rod introduced into theextension volume 74. During rebound, fluid flows from the extensionvolume 74, through the integrated piston head 71, and into thecompression volume 73. Simultaneously, the floating piston 75 moves toexpand the accumulator gas volume 76 to compensate for the piston rodvolume leaving the housing during rebound.

When fluid flows through the integrated piston head 71, the hydraulicmotor spins, which turns the electric generator. This generateselectricity from the movement of the fluid forced through the pistonhead 71 by the movement of the piston 30. The energy from the electricgenerator is transmitted via wires 29 that exit the IPH, through thehollow piston rod 30, and exit outside the damper housing at the end ofthe piston rod via the rod end 77. High pressure pass-throughs 31 may beused to seal the portion of wires that are immersed in hydraulic fluidwith the electric generator from wire portions that exit the piston rodto the outside environment.

By altering the electrical characteristics of the electric generator,the kinematic characteristics of the damper can be altered. If the loadis increased on the electric generator by applying lower impedance onthe terminals, the force/velocity characteristic of the generator willbe increased (greater force per angular velocity). Since the hydraulicmotor and electric generator are coupled, this is translated to thehydraulic motor and therefore the fluid path through the integratedpiston head. The linear relationship results in an increasedforce/velocity characteristic on the damper piston when lower impedanceis applied to the generator, and a decreased force/velocitycharacteristic on the damper piston when higher impedance is applied tothe generator.

Likewise, the electric generator can be driven as a motor, and thehydraulic motor can be utilized as a hydraulic pump. This allows foractuation of the damper, creating an active linear actuator. An exampleof such usage, using the embodiment of FIG. 4 as an illustrativeexample, is to drive the electric motor/generator 18 by applying avoltage. By way of example, a brushed DC motor may be used as thegenerator and a gerotor pump may be used as the hydraulic motor,however, the present invention(s) is not limited in this regard. Whenvoltage is applied to the electric generator 18, the hydraulic motormechanism will spin, forcing fluid from either the compression volume 73to the extension volume 74, or vice-versa, depending on direction ofspin (which is governed by voltage polarity for a DC motor/generator).The movement of fluid from one volume to the other forces the pistonhead to move, actuating the piston rod. In some applications, this maybe useful as an active suspension system in vehicles to allow forcontrollable placement of the wheels for improved ride comfort andterrain traversal characteristics. In some industrial applications, thismay be useful as a stand-alone, sealed hydraulic actuator with a highpower density characteristic.

In one embodiment, the gas in the accumulator 76 should be pressurizedso as to ensure the maximal compression (jounce) damping does not exceedthe force applied by the accumulator 76 on the compression volume 73. Inone embodiment, the pressure is typically in the 200-800 psi range,however, an appropriate value can be calculated as follows: accumulatorpressure >max jounce damping force/floating piston surface area.

The embodiment of FIG. 4A shows a monotube damper of the arrangementshown in FIG. 4 whereby the IPH 71 is of the embodiment as shown in FIG.3. Here, the IPH 72 is connected to a piston head 150 that is connectedto the piston rod 30. The seal 151 is contained in the piston adaptor,thereby allowing the IPH 72 to be common with other damper arrangements,as shown in FIG. 6 for example. It is of course possible for the seal tobe housed directly in the IPH 71, and the IPH to be connected directlyto the piston rod 30.

Some embodiments of the described monotube damper incorporating anintegrated piston head 1 include additional features. Applications suchas vehicle dampers sometimes require minimal damping during jounce. Inorder to reduce the damping during jounce compared to the fluid paththrough the hydraulic motor, a check valve “bypass” 42 may beincorporated in the integrated piston head (or elsewhere) such thatfluid may flow from the compression volume to the extension volume viathe bypass valve, but not vice-versa. Additionally, other valving suchas non-directional valves, bypasses and blow-off valves 44 may be usedto further tune ride characteristics.

In some cases it is desirable to eliminate the gas-filled accumulatorand operate the system at low-pressure to minimize the possibility offluid leakage through the shaft seals. Additionally, it may be desirableto locate the electric generator off of the piston head (e.g. to allowfor a larger motor without compromising piston stroke to housing lengthratio). FIG. 5 demonstrates one embodiment of an integratedenergy-generating damper that is operated at low pressure, locates theelectric generator off the piston head, and features a compressionbypass.

The twin-tube damper embodiment of FIG. 5 has a piston head 81 disposedin an inner housing that includes a compression volume 79 and anextension volume 80. In a first mode, the piston 81 moves through atleast a portion of a jounce stroke to pressurize hydraulic fluid in thecompression volume 79. In a second mode, the piston moves at leastpartially through a rebound stroke to pressurize hydraulic fluid in theextension volume 80. An outer tube concentric to the inner tube containsthe low-pressure volume 82. The low-pressure volume 82 contains bothfluid and a compressible medium (such as gas, foam or bladder). Thepiston head 81 disposed in the inner housing contains an integratedhydraulic motor 83 that includes a first port 84 and a second port 85.The first port 84 is in fluid communication with the compression volume79 and the second port 85 is in fluid communication with the extensionvolume 80. The piston rod 86 is hollow and contains a shaft 87 thatconnects the hydraulic motor 83 on the piston head 81 with an electricmotor/generator 89 on the other end of the piston rod 86. Rotation ofthe hydraulic motor 83 causes rotation of the electric motor/generator89.

In the embodiment of FIG. 5, rebound damping is provided by the electricmotor/generator 89 and delivered via the shaft 87 inside the piston-rod86. The resistive force on the shaft 87 is delivered to the hydraulicmotor 83 to restrict fluid flow between the compression volume 79 andthe extension volume 80. As discussed previously, the kinematiccharacteristic of the damper can be altered by varying the electricalcharacteristics on the terminals of the electric motor/generator. Inaddition, the system can be actively driven by supplying power to theelectric motor/generator.

Valves 90, 91 restrict flow into and out of the low-pressure volume 82such that during jounce fluid flows from the compression volume 79,through the unrestrictive open valve 90, and freely flows through thelow-pressure volume 82, through the check valve 91 into the extensionvolume 80. During rebound, the check valve 91 closes, forcing fluid fromthe extension volume 80 to go through the piston head 81, while a smallamount of fluid to replace exiting piston rod volume flows from thelow-pressure volume 82, through the open valve 90, into the compressionvolume 79.

In the twin-tube embodiment of FIG. 5, during jounce, pressurized fluidin the compression volume 79 flows through the open valve 90, into thelow-pressure volume 82, and exits the check valve 91 to the extensionvolume 80. In this embodiment, the volume of fluid entering the openvalve 90 is greater than that exiting the check valve 91, and thisvolume differential is stored in the low-pressure volume by compressingthe compressible medium therein. In addition to this fluid path, somefluid may pass from the compression volume 79, through the piston head81, into the extension volume 80, generating electricity in thegenerator 89 while doing so.

During rebound, the embodiment of FIG. 5 will pressurize fluid in theextension volume 80, thereby closing the check valve 91. Fluid is forcedto flow from the extension volume 80, through the piston head 81, intothe compression volume 79. Simultaneously, stored fluid in thelow-pressure volume 82 will flow through the open valve 90 into thecompression volume 79 to replace piston rod volume as the compressiblemedium in the low-pressure volume 82 expands. As fluid flows from thecompression volume 80, through the porting 85, into the hydraulic motor83, out from the porting 84, into the extension volume 79, the hydraulicmotor 83, spins. This spins the shaft 87 that runs inside the piston rod86 and the motor/generator 89 so that this fluid flow generates backelectromotive force (EMF) from the motor/generator to provide damping.

In the embodiment shown in FIG. 5, an offset loop 93 is used to attachthe piston rod 86 to the vehicle, however, any suitable attachmentmethod may be employed such as loop connectors or threaded piston rodmounts. In the system of FIG. 5, the electric generator is placed abovethe mount point for the piston rod. Several embodiments allow for this.In one embodiment, the shaft 87 passes through a shaft seal thatseparates a fluid-contained side of the shaft from an open-air side ofthe shaft. In one instance, this allows a keyed shaft 87 to insert intothe electric generator can 92 which can thread onto the piston rod,acting as the primary mount apparatus for the piston rod end of thedamper. In another embodiment, an offset loop adapter is used on the topand bottom to allow a bolt-on attachment without side-loading thedamper. Here, there entire length of shaft 87 and the generator 92 canbe enclosed in fluid during production, eliminating the need for apressure shaft seal for field installation. In another embodiment, anadapter can be attached to the piston rod to allow for either an eyeletmount point or a piston rod nut mount attachment method without the needfor threading on the generator can during installation. Again, thisallows for the elimination of a friction-causing shaft seal on the motorshaft 87. Several attachment methods for the piston rod end of thedamper were presented, however, the present invention is not limited inthis regard.

FIG. 6 demonstrates another embodiment of an integratedenergy-generating damper that is operated at low pressure, locates theelectric generator off the piston head, and features a compressionbypass, similar to that shown in FIG. 5, differing in the fact that theto motor/generator is not disposed on the opposite end of the piston rodfrom the piston head, but positioned perpendicular to the cylinder body.This arrangement offers the benefit of shorter overall shock length, aswell as eliminating the need for long thin concentric shafts. Thisarrangement may be more suitable for vehicular damper applications whereshock length and packaging requirements are constrained.

The twin-tube damper embodiment of FIG. 6 includes a piston 94 disposedin an inner housing that includes a compression volume 95 and anextension volume 96. In a first mode, the piston 94 moves through atleast a portion of a jounce stroke to pressurize hydraulic fluid in thecompression volume 95. In a second mode, the piston moves at leastpartially through a rebound stroke to pressurize hydraulic fluid in theextension volume 96. An outer tube concentric to the inner tube containsthe low-pressure volume 97. The low-pressure volume 97 contains bothfluid and a compressible medium 98 (such as gas, foam or bladder). Anintegrated motor/generator unit (IMGU) 72 is located at the rod end ofthe damper. The IMGU shown in FIG. 6 is similar to that as shown in FIG.3, but it may be similar to that as shown in FIG. 1 or FIG. 2, andincludes a first port 100 and a second port 101. The first port 100 isin fluid communication with the low pressure volume 97 and the secondport 101 is in fluid communication with the extension volume 96.

A valve 102 restricts flow into and out of the low-pressure volume 97such that during jounce fluid flows from the compression volume 95,through the valve 102, and into the low-pressure volume 97. The valve102 offers the required flow resistance in this direction so as to givethe appropriate jounce damping characteristics for the application.During rebound, the valve 102 allows for free flow from the low-pressurevolume 97 into the compression volume 95.

In the twin-tube embodiment of FIG. 6, during jounce, pressurized fluidin the compression volume 95 flows through the valve 102, into thelow-pressure volume 97, into the IMGU 72 through port 100, exiting theIMGU through port 101 and into the extension volume 96. In thisembodiment, the volume of fluid exiting the compression volume 95 isgreater than that entering the extension volume 96 and this volumedifferential is stored in the low-pressure volume 97 by compressing thecompressible medium 98 therein. During rebound, the embodiment of FIG. 6will pressurize fluid in the extension volume 96 forcing flow from theextension volume 96, through the IMGU 72 via ports 101 and 102, into thelow pressure volume 97, through the open valve 102 into the compressionvolume 95. Simultaneously, stored fluid in to the low-pressure volume 97will also flow through the open valve 102 into the compression volume 95to replace piston rod volume, as the compressible medium 98 in thelow-pressure volume 97 expands. As fluid flows from the extension volume96, through the porting 101 into the IMGU 72, and out of the IMGU fromthe porting 100 back into the compression volume 96, the hydraulic motor55 and generator 50, spins. This generates back electromotive force(EMF) from the motor/generator to provide damping and produceselectricity as described in FIG. 2. As discussed previously, thekinematic characteristic of the damper can be altered by varying theelectrical characteristics on the terminals of the electricmotor/generator. In addition, the system can be actively driven bysupplying power to the electric motor/generator.

In the embodiment shown in FIG. 6 during jounce, fluid that flows fromthe compression volume 95 through the valve 102 into the low-pressurevolume 97 then flows into the IMGU 72 through port 100, exiting the IMGUthrough port 101 and then into the extension volume 96. The fluid thatflows through the IMGU during the jounce stroke will cause the motor 55and generator 50 to spin, and although no back EMF will be produced,because of the low jounce damping forces required, the parasitic lossesfrom the fluid flow and the rotating parts may cause too high a jouncedamping force for certain applications. In these applications, it ispossible to incorporate a bypass check valve 105 that will communicatethe low pressure volume 97 to the compression volume 96. The check valvewill allow the fluid to free flow directly from the low pressure volume97 to the compression volume 96, thereby reducing the jounce dampingforce, but will not allow flow to bypass the IMGU during rebounddamping.

In the embodiment shown in FIG. 6 there is a volume of oil that becomestrapped between the pockets 103 of the piston 94 and the journals 104 ofthe end caps during the last portion of both the jounce and reboundstrokes. When the piston 94 is stroked so that the journal 104 entersthe pocket 103 (in either jounce or rebound strokes) the hydraulic fluidthat is trapped in the pocket 103 is forced to flow out of the annulargap that is formed between the journal outside diameter and the pockedinside diameter. The annular gap is sized so that a pressure spike isproduced acting over the pocket area producing an additional force toprovide a hydraulic buffer at the end of both the jounce and reboundstrokes. The clearance between the pockets 103 and the journal 104 canbe selected so as to produce the correct amount of buffering to suit theapplication.

In some use scenarios, it is desirable to have an energy-generatingdamper that is not gas-pressure limited in compression damping, featuresenergy capture in both compression and to rebound, and maximizes strokelength per body length. Several embodiments that will now be describedthat incorporate the above features.

According to the embodiment shown in FIG. 7, a tri-tube damper designthat incorporates an energy-harvesting IMGU is disclosed. In thisembodiment, a piston rod 105 and hydraulic-ram type (solid) piston 106are disposed in an inner fluid-filled cylinder 107. The inner housing(collectively, the compression volume 108 and the extension volume 109)is surrounded by a second tube 110 that is concentric to the inner tube107. The space between the inner tube and the second tube contains thehigh-pressure volume 111. The second tube 110 is surrounded by a thirdtube 112 that is concentric to the second tube. The space between thesecond tube and the third tube contains the low-pressure volume 112. Insome embodiments the high-pressure and low-pressure tubes may bereversed.

In the embodiment of FIG. 7, an integrated motor/generator unit (IMGU)72 is located at the rod end of the damper. The IMGU shown in FIG. 7 issimilar to that as shown in FIG. 3, alternatively, it may be similar tothat as shown in FIG. 1 or FIG. 2, and includes a first port 113 and asecond port 114. The first port 113 is in fluid communication with thehigh-pressure volume 111 and the second port 114 is in fluidcommunication with the low-pressure volume 112.

During jounce, the piston rod 105 pushes the piston 106 into thecompression volume 108, this forces fluid to pass from the compressionvolume into the high pressure volume 111 via a directional check valve115. The high pressure volume 111 is in fluid communication with thefirst port 113 of the IMGU 72. Fluid passes from the high pressurevolume 111, through the first port 113, through the IMGU 72, and out thesecond port 114, into the low pressure volume 112, through a directionalcheck valve 116, and into the extension volume 109. Simultaneously, acompressible medium 117 such as foam cell, or bladder, in thelow-pressure volume 112 compresses to displace introduced piston rodvolume.

During rebound, the piston rod 105 pulls the piston 106 into theextension volume 109, this forces fluid to pass from the extensionvolume into the high pressure volume 111 via a directional check valve118. The high pressure volume 111 is in fluid communication with thefirst port 113 of the IMGU 72. Fluid passes from the high pressurevolume 111, through the first port 113, through the IMGU 72, and out thesecond port 114, into the low pressure volume 112, through a directionalcheck valve 119, and into the compression volume 108. Simultaneously,the compressible medium 117 in the low-pressure volume 112 decompressesto replace extracted piston rod volume.

As fluid flows from the high pressure volume 111, through the porting113 into the IMGU 72, and out of the IMGU from the porting 114 back intothe low pressure volume 112, the hydraulic motor 55 and generator 50rotate. This generates back electromotive force (EMF) from themotor/generator to provide damping and produces electricity as describedin the embodiment of FIG. 2. As discussed previously, the kinematiccharacteristic of the damper can be altered by varying the electricalcharacteristics on the terminals of the electric motor/generator. Inaddition, the system can be actively driven by supplying power to theelectric motor/generator.

According to another embodiment, FIG. 8 shows a twin-tube design that isnot gas-pressure limited, featuring bidirectional energy capture, andhaving a high stroke to body length ratio. This system utilizes theintegrated piston head of FIG. 2 (although this could also be the IPH asshown in FIG. 1 or 3), in a twin-tube body design with the use of avalve mechanism that operates to ensure that whichever port is at lowpressure is always connected to the accumulator. Pilot operated valvessuch as check valves or a three port pilot operated spool valve mayaccomplish this operation. A shuttle valve can also ensure that the gasaccumulator 124 on the common port is always in fluid communication withthe low-pressure side of the piston head.

In the embodiment shown in FIG. 8, an integrated piston head 71 isdisposed in an inner cylinder containing hydraulic fluid. The extensionvolume 120 of the inner cylinder is in fluid communication with an outerfluid volume 121 which is housed between the inner cylinder and aconcentric outer cylinder. Both the compression volume 122 and the outerfluid volume 121 are in fluid connection with a pilot-operated valveblock 123. A gas-filled accumulator, or reservoir, 124 is also in fluidconnection with the pilot-operated valve block 123.

During jounce, the piston rod 30 is pushed into the cylinder, forcingfluid from the compression volume 122 through the hydraulic motor 16,which spins an electric motor/generator 18, and passes into theextension volume 120. Electricity from the electric generator passesdown wires that go through the center of the piston rod 30.High-pressure wire pass-throughs seal the fluid portion of the internalshock body from the outside. Since the jounce stroke introduces pistonrod volume into the extension volume, fluid needs to be displaced fromthe extension volume to an accumulator 124, which occurs via a valveblock 123. When the compression volume becomes pressurized, a pilotoperated check valve 125 is opened in the valve block 123 via the pilotline 127. This allows free flow to and from the accumulator 124 to theextension volume 120, thereby allowing the introduced rod volume to flowfrom the extension volume into the accumulator 124.

During rebound, the piston rod 30 is pulled out of the cylinder, forcingfluid from the extension volume 120 through the hydraulic motor 16,which spins an electric motor/generator 18, and passes into thecompression volume 122. Since the rebound stroke extracts piston rodvolume from the compression volume, fluid needs to be displaced from theaccumulator 124, which occurs via a valve block 123. As the rod volumewill need to be replaced into the compression volume from theaccumulator, the pressure in the compression volume will be lower thanthat of the accumulator, this will allow for fluid to flow from theaccumulator 124 through the check valve 126 into the compression volume122.

In the embodiment shown, the valve block 123 comprises of a check valve126 and a pilot operated check valve 125 to ensure that whichever portof the IPH is at low pressure is always connected to the accumulator,however, this can also be achieved using other valving arrangements suchas a spool valve mechanism that can switch the connection of theaccumulator 124 between the compression volume 122 and the extensionvolume 120 so that the accumulator is always in fluid communication withthe lower pressure volume. In this embodiment, during jounce thepressure in the compression volume 122 is greater than the pressure inthe extension volume 120, an internal pilot port in the valve block 123,connected to the compression volume 122 pushes the shuttle mechanismsuch that fluid can communicate between the accumulator 124 and theextension volume 120. During rebound, the pressure in the extensionvolume 120 is greater than the pressure in the compression volume 122,an internal pilot port in the valve block 123 connected to the extensionvolume 120 pushes the shuttle mechanism such that fluid can communicatebetween the accumulator 124 and the compression volume 122. Shuttlevalve mechanisms, other pilot-operated valves, and valves thatselectively connect different fluid volumes based on pressuredifferentials (including mechanical and electrically actuated valves)are well known in the art, and are not limited in the presentinvention(s).

While the hydraulic motor 16 and electric motor/generator 18 are shownin an integrated piston head 71 configuration, the embodiment of FIG. 8can also be constructed with the piston head, piston rod, and electricmotor/generator configuration of FIG. 5, where the piston head containsa hydraulic motor, the piston rod contains an internal spinning shaft,and the electric motor/generator is on the opposing side of the pistonrod. In another embodiment, the system of FIG. 8 can be constructed witha solid piston head and a hydraulic motor and generator pair that sitsat the base of, and external to, the damper such as the system disclosedin FIG. 6. Here, the first port of the hydraulic motor would be in fluidcommunication with the compression volume 122 and second port would bein fluid communication with the extension volume 120 (via the outerfluid volume 121). The rest of the system including the valve block 123may remain as shown in FIG. 8.

Certain industrial applications of a sealed hydraulic linear energygenerator allow for alternative form factors than typical automotivedampers. In the embodiment of FIG. 9, a through-shaft integrated pistonhead system is demonstrated. In this embodiment, an integrated pistonhead 128 is disposed in a cylinder containing hydraulic fluid connectedto a first piston rod 129 and a second piston rod 130. The piston headas shown in FIG. 9 is similar to that as shown in FIG. 3, but it may besimilar to that as shown in FIG. 1 or FIG. 2. In some embodiments thesecond piston rod 130 exiting the device may be connected to a springmechanism in order to return the other piston rod to a normallycompressed state.

During piston rod travel in a first direction, fluid from the firstvolume 131 is forced to flow through the hydraulic motor 132, whichspins an electric motor/generator 133, and passes into the second volume134. Electricity from the electric generator passes down wires that gothrough the center of one of the piston rods where high-pressure wirepass-throughs seal the fluid portion of the internal shock body from theoutside.

During piston rod travel in a second direction, fluid from the secondvolume 134 is forced to flow through the hydraulic motor 132, whichspins an electric motor/generator 133, and passes into the first volume131.

Internal to the system is a device to displace fluid to compensate forfluid volume changes due to temperature fluctuations. In the embodimentof FIG. 9, this is shown to be compressible foam cell inserted into acrevice 135 in one of the piston rods 134. However, placement of thefluid compensation mechanism may be in another location internal to theunit or external. Additionally, an accumulator, among other devices, canbe used as a replacement or in addition to foam in order to displacefluid. In some embodiments, it may be desirable to limit to pressure thefluid compensation mechanism encounters. In these embodiments, a shuttlevalve may be employed as described in FIG. 8.

In certain applications, such as heavy duty military vehicles, it isdesirable to have an energy harvesting rotary damper. The embodiment ofFIG. 10 demonstrates such as system whereby an IntegratedMotor/generator Unit (IMGU) is connected to a rotary damper unit 136. Inthe embodiment shown the IMGU 72 is similar to that as shown in FIG. 3,but it may be similar to that as shown in FIG. 1 or FIG. 2. During thedamper lever stroke in a first direction, fluid from the first volume(s)138 is forced to flow into the first port 59 through the hydraulic motor55 and out through the second port 60 into the second volume(s) 139. Asfluid flows through the motor 55 the motor and generator spins andgenerates electricity, as described in FIG. 7. During the damper leverstroke in a second direction, fluid from the second volume(s) 139 isforced to flow into the second port 60 through the hydraulic motor 55and out through the first port 59 into the first volume(s) 138. As fluidflows through the motor 55, the motor and generator spins and generateselectricity, as described in FIG. 7. A device to displace fluid tocompensate for fluid volume changes due to temperature fluctuationsmaybe incorporated either internally or externally by way of acompressible foam cell or an accumulator, among other devices.

In the embodiment shown the IMGU is shown as an external device to therotary damper, however, the IMGU can be easily integrated into rotarydamper mechanism, thereby reducing the overall package size andeliminating external hydraulic connections.

Other rotary damper configurations may be employed and it may bepossible to incorporate the energy harvesting IPH or IMGU into thesedevices as the present invention is not limited in this regard.

Certain industrial applications of electro hydraulic linear actuatoroffer the ability to capture energy in the opposite direction to theiractuation, such as in lifting equipment where a mass is being raised andthen lowered. In the embodiments shown in FIG. 11 and FIG. 11A, atwin-tube energy harvesting electro hydraulic linear actuator that iscapable of capturing energy in the compression stroke and poweractuation in the extension stroke is presented.

In the embodiment shown in FIG. 11 the IPH valve is placed at the baseof the actuator concentric with the actuator, it is possible to locatethe IPH valve at the base of the actuator body, but perpendicular to theaxis of the actuator as shown in the embodiment shown in FIG. 11A, (theIPH valve may also be placed at the base of the actuator body, butparallel to the to actuator axis). This may offer packaging benefits incertain applications where actuator length is critical.

The twin-tube embodiments of FIG. 11 and FIG. 11A have a piston 140disposed in an inner housing 141 that includes a compression volume 142and an extension volume 143. In a first mode, the compression volume 142is pressurized and moves the piston 140 through at least a portion of anextension stroke to overcome a force. In a second mode, the piston movesat least partially through a compression stroke to pressurize hydraulicfluid in the compression volume 142 from a force. An outer tube 144concentric to the inner tube 141 contains a low-pressure volume 145 thatis in fluid communication with the extension volume via passages 146.The low-pressure volume 145 contains both fluid and a compressiblemedium 147 (such as gas, foam or bladder). An integrated piston head(IPH) assembly 71 (72 in FIG. 11A) is located at the base of theactuator. The IPH assembly may be similar to that as shown in FIG. 1,FIG. 2 or FIG. 3, and includes a first port 148 and a second port 149.The first port 148 is in fluid communication with the compression volume142 and the second port 149 is in fluid communication with the lowpressure volume 145. In the twin-tube embodiment of FIG. 11 and FIG.11A, during extension, power is supplied to the electric motor/generator18 causing it and the hydraulic motor 16 to spin, this causes fluid toflow from the hydraulic motor via port 148 into the compression volume142. This generates pressure in the compression volume so as to generatea force on the piston 140 overcoming the force present on the pistonrod, causing the piston to extend. As the piston extends, fluid isdisplaced from the extension volume 143 and flows through the lowpressure chamber 145, through the second port 149 and into the lowpressure side of the hydraulic motor 16. In this embodiment, the volumeof fluid entering the compression volume 142 is smaller than thatexiting the extension volume 143 and this volume differential is takenfrom the stored volume in the low-pressure volume 145 by expanding thecompressible medium 147 therein.

A load holding valve (such as a check valve) may be placed between thefirst port 148 and the compression volume 142 to eliminate leakagethrough the hydraulic motor when the actuator is under load holdingoperation. This will prevent the piston from retracting under loadholding causing a safety hazard. The load holding valve might be of thepilot operated, electronically activated or mechanically activated type,these valves are well known in the art and the patent is not limited inthis regard.

In this embodiment, retraction of the piston may be accomplished in twoways, in the to first mode, where there exists an external load on thepiston rod (when the actuator is used in lowering a payload forexample); the piston will want to retract under this force. If a loadholding valve is used then the piston will not retract until this valveis activated to allow fluid flow from the compression volume 142 to thefirst port 148. Once this valve is activated (via electronic, mechanicalmeans etc.), then fluid will flow from the compression volume 142 to thefirst port 148, due to the load place upon the piston rod, and willcause the motor 16 to spin. This will cause the generator 18 to spingenerating back electromotive force (EMF) from the motor/generator toprovide resistance to this flow, and producing electricity as describedin FIG. 2. A controller may provide varying impedance to the electricgenerator, thereby controlling rate at which the fluid flows from thecompression volume to the first port, offering a controllable and safemanner in which to lower the payload.

In the second mode where there is no payload acting on the actuator, thepiston is retracted by supplying power to the electric motor/generator18 causing the electric motor/generator 18 and the hydraulic motor 16 tospin, this causes fluid to flow from the from the compression volume 142to the first port 148, pressurizing the low pressure volume 145 and theextension volume 143, thereby retracting the piston 140. Although thiswill require the low pressure volume to become pressurized, the load toretract the piston in this application will be very low, as it will needto only overcome friction of the actuator and any accompanyingmechanism, and as such the pressure attained in the low pressure volumewill be within the limits of the compressible medium contained therein.If a load holding valve is utilized as described above, then actuationof this valve will first have to take place before the piston isretracted.

During retraction of the piston, fluid will flow from the compressionvolume 142 into the first port 148, through the motor 16, into the lowpressure volume 145, via the second port 149, and into the extensionvolume 143. In the embodiment shown, the volume displaced by thecompression volume is greater than that entering the extension volumeand this volume differential is stored in the low-pressure volume 145 bycompressing the compressible medium 147 therein.

Certain applications of the energy harvesting electro hydraulic linearactuator as shown in the embodiment of FIGS. 11 and 11A, may require theaddition of other valves such as pressure relief valves, thermal reliefvalves etc. and the incorporation of these valves are well to known inthe art of this type of actuator and the patent is not limited in thisregard.

In certain energy harvesting applications, it may be advantageous tokeep the motor/generator assembly rotating in the same directionregardless of stroke direction. For these applications it is possible toconnect the motor/generator assembly to the actuator (be it a linear orrotary type) via a rectifying valve circuit. In the embodiment shown inFIG. 12 an energy harvesting linear actuator that is connected to anintegrated motor/generator assembly via a rectifying valve circuit ispresented. In the embodiment shown the rectifying valve circuit 150 isin the form of four check valves, however, the same functionality can ofcourse be achieved by the use of a pilot operated spool valve(s) or thelike, and the patent is not limited in this regard.

In the embodiment shown, the integrated motor/generator assembly issimilar to that as shown in FIG. 3, but it may be similar to that asshown in FIG. 1 or FIG. 2, and includes a first port 151 and a secondport 152. The first port 151 is in fluid communication with thedischarge side of the rectifying circuit and the second port 152 is influid communication return side of the rectifying circuit. In theembodiment shown the linear actuator is in the form of a twin tubearchitecture which has a first port 153 that is in fluid connection withthe extension side of the actuator and a second port 154 is in fluidconnection with the compression side. A piston 155 disposed in an innerhousing that includes an extension volume 156 and a compression volume157. In a first mode, the piston 155 moves through at least a portion ofan extension stroke to pressurize hydraulic fluid in the extensionvolume 156. In a second mode, the piston moves at least partiallythrough a compression stroke to pressurize hydraulic fluid in thecompression volume 157. An outer tube concentric to the inner tubeconnects the compression volume 157 to the second port 154.

The rectifying circuit is configured so that fluid that is dischargedfrom the first port of the actuator during an extension stroke or thesecond port during a compression stroke will always be diverted to thedischarge side of the rectifying circuit and into the first port of theIMGU 72, and fluid discharged from the second port 152 of the IMGU willalways be diverted to the first port 153 of the actuator during acompression stroke or the second port 154 during an extension stroke.This will ensure that the direction of rotation of the motor/generatorwill remain constant regardless of whether the actuator is extended orretracted under load.

An accumulator or reservoir 158 is connected to the second port 152 ofthe IMGU 72 to accommodate the difference in volume from the extensionand compression strokes. In the to embodiment shown the reservoir isconnected to the symmetrical port opposite the second port 152, althoughthis could be connected anywhere along the return line of the rectifyingcircuit.

One issue with using a rectifier circuit with the energy harvestingactuator is the fact that the motor/generator cannot back drive theactuator, and the motor/generator can ‘freewheel’ under certain inertialconditions. This can be overcome however by replacing the check valves(or spool valves) with pilot operated valves (that are eitherelectrically, or mechanically operated), and then sequencing the valvesso that the discharge from the hydraulic motor via first port 151 is influid connection with the first port 153 of the actuator as the secondport 152 of the hydraulic motor is in fluid connection with the secondport 154 and vice versa.

Certain applications such as industrial, military and aerospace, mayrequire a higher performance hydraulic power supply, in terms ofpressure capacity and efficiency to deliver the required power density.In the embodiment of FIGS. 13 and 13A, an integrated motor/generatorunit, comprising of an axial piston unit positioned concentric andcoplanar with the generator is shown. This embodiment is similar to thatshown in FIG. 3, but the hydraulic unit is now an axial piston unit(i.e. a swashplate unit) as opposed to a gerotor pump. A swashplate pumpmay offer high performance, in terms of pressure capacity, speed,efficiency and durability, when compared to other types of hydraulicpumps.

In the embodiment shown, the cylinder block 160 of the axial piston unit159 is drivingly connected to the magnets 161 of the generator 162 andis supported by bearings 163 to the end caps 164 and 165. The end cap163 contains a first port 166 and second port 167 that are arranged toact as a commutation plate to direct flow into and out of the cylinderblock 160 via passages 168. A swashplate 169 is located opposite thecylinder block passages 168 on the end cap 165. A plurality of pistons170 are contained within the bores of the cylinder block 160 and areheld against the swashplate by the piston feet 171. The method in whichthe pistons are help against the swashplate and are forced to cam in andout of the cylinder bores is well known in the art, and it is not in thescope of this patent to define these actions, also the method in whichthe cylinder block is loaded against the commutation plate (via springsor other means) is similarly known.

When electrical power is fed into the generator, it will act as anelectric motor and cause the cylinder block 160 to rotate, this in turnwill cause pumping via the pistons 170, and flow will take place via thefirst and second ports. The direction of flow will be dependent upon thedirection of rotation of the cylinder block which is turn dependent uponthe direction of current to fed into the electric motor. Conversely ifeither the first or second port is pressurized then the axial pistonunit will act as a motor and will spin under this pressure differential.This will in turn generate electricity via the generator as describedpreviously.

By controlling the speed of the electric motor, the speed and hence theflow rate, of the axial piston unit can be varied without having to varythe swept displacement of the unit. Many variations of variabledisplacement axial piston pumps exist, and whilst they have theadvantage of being able to control the flow rate to meet the demand,they all have the disadvantage that as their swept displacementapproaches zero, their volumetric efficiency decreases.

The benefit of arranging the axial piston unit concentric and coplanarwith the motor/generator is that an axial piston pump, which is of equalor smaller size than a variable displacement axial piston pump, will beable to offer a variable flow rate whilst remaining at its maximum sweptdisplacement, thereby maintaining its volumetric displacement.

In some use scenarios, it is desirable to have an energy-generatingdamper that is not gas-pressure limited in compression damping, featuresenergy capture in both compression and rebound, the embodiments shown inFIG. 14 and in FIG. 14A will now be described that incorporate the abovefeatures.

According to the embodiments shown in FIG. 14 and in FIG. 14A, atri-tube damper design that incorporates an energy-harvesting IMGU isdisclosed. In this embodiment, a piston rod 172 and hydraulic-ram type(solid) piston 173 are disposed in an inner fluid-filled cylinder 174.The inner housing (collectively, the compression volume 175 and theextension volume 176) is surrounded by a second tube 177 that isconcentric to the inner tube 174. The space between the inner tube andthe second tube contains the high-pressure volume 178. The second tube177 is surrounded by a third tube 179 that is concentric to the secondtube. The space between the second tube and the third tube contains thelow-pressure volume 180. In some embodiments the high-pressure andlow-pressure tubes may be reversed.

In the embodiment of FIG. 14, an integrated motor/generator unit (IMGU)72 is side located at the base end of the damper and in the embodimentof FIG. 14A, an integrated motor/generator unit (IMGU) 72 is located atthe base end of the damper. The IMGU shown in

FIG. 14 and FIG. 14A is similar to that as shown in FIG. 3,alternatively, it may be similar to that as shown in FIG. 1 or FIG. 2,and includes a first port 181 and a second port 182. The first port 181is in fluid communication with the high-pressure volume 178 and thesecond port 182 is in fluid communication with the low-pressure volume180.

During jounce, the piston rod 172 pushes the piston 173 into thecompression volume 175, the fluid in the compression volume 175 isblocked from flowing into the low pressure volume by a directional checkvalve 183, and is forced to flow from the compression volume 175 intothe extension volume 176 via a directional check valve 184 contained inthe piston 173. As the volume displaced in the compression chamber isgreater than the volume created in extension chamber by the volume ofthe piston rod 172, the volume differential passes through the highpressure volume 178 into the first port 181 of the IMGU 72, and out thesecond port 182, into the low pressure volume 180. Simultaneously, acompressible medium 185 such as foam cell, or bladder, or gas volume inthe low-pressure volume 180 compresses to displace introduced piston rodvolume.

During rebound, the piston rod 172 pulls the piston 173 into theextension volume 176, the fluid in the extension volume 176 is blockedfrom flowing into the low compression volume by the directional checkvalve 184 and is forced to pass from the extension volume into the highpressure volume 180. The high pressure volume 180 is in fluidcommunication with the first port 181 of the IMGU 72. Fluid passes fromthe high pressure volume 180, through the first port 181, through theIMGU 72, and out the second port 182, into the low pressure volume 180,through a directional check valve 183, and into the compression volume175. Simultaneously, the compressible medium 185 in the low-pressurevolume 180 decompresses as fluid passes from the low pressure chamber180 through the directional check valve 183 into the compression volumeto replace the extracted piston rod volume.

As fluid flows from the high pressure volume 178, through the porting181 into the IMGU 72, and out of the IMGU from the porting 182 back intothe low pressure volume 180, the hydraulic motor 55 and generator 50rotate. This generates back electromotive force (EMF) from themotor/generator to provide damping and produces electricity as describedin the embodiment of FIG. 2. As discussed previously, the kinematiccharacteristic of the damper can be altered by varying the electricalcharacteristics on the terminals of the electric motor/generator. Inaddition, by supplying power to the electric motor/generator the dampingforce of the system can be increased beyond the range of that offered bythe back EMF under power regeneration mode, or decreased below thatoffered by the resistance from the system open-circuit parasitic losses.The motor/generator can be driven so that the fluid flow from thehydraulic motor resists fluid flow from the damper, in eithercompression or rebound, thereby increasing the damper force, or it canbe driven so that the fluid flow from the hydraulic motor to assistsfluid flow from the damper, in either compression or rebound, therebydecreasing the damper force. The motor/generator can also be driven sothat the fluid flow from the hydraulic motor resists fluid flow from thedamper to the point that the damper is held stationary. However in thisembodiment, the damper cannot be actively driven so that the damper willextend or retract from power being supplied to the motor/generator. Thepresent invention is not limited in this regard, however, and when usedin a monotube configuration, for example, is able to extend and retractfrom power being supplied to the motor/generator without additionalvalving. In the triple-tube arrangement, if the motor/generator isdriven to extend the damper, fluid flow from the second port 182 willfree flow through the check valves 183 and 184 back into the first port181, and if motor/generator is driven to retract the damper then fluidflow from the first port 181 will pressurize the extension chamber 176,which will in turn pressurize the compression chamber 175, however thecheck valve 183 will block any flow from the compression chamber therebynot allowing retraction of the piston rod.

In some use scenarios it is desirable to be able to actively extend orretract the damper by supplying power to the motor/generator andadditional valves may be be required depending on the embodiment. Theembodiment shown in FIG. 15 will now be described that incorporatesadditional valves. According to the embodiment shown in FIG. 15, atri-tube damper design that incorporates an energy-harvesting IMGU 72similar to that shown in FIG. 14 is disclosed (alternatively, it may besimilar to that shown in FIG. 14A). In this embodiment, controlledvalves 186 and 187 are incorporated to allow the damper to be activelyextended or retracted by supplying power to the motor/generator. Thecontrolled valves 186 and 187 may be controlled electronically orhydraulically or by other means.

When the damper is required to be extended, electrical power is suppliedto the motor/generator so that there is fluid flow from the first port181 of the IMGU 72 to the high pressure chamber 178. The controlledvalve 186 is held closed and the controlled valve 187 is opened to allowfluid flow from the high pressure chamber 178 to the compression chamber175, the check valve 183 closes to block flow from the compressionchamber 175 to the low pressure chamber 180. As the high pressurechamber 178 is in fluid communication with the extension volume 176,pressure will now exist on both the extension side and compression sideof the piston 173, and because of the area differential across thepiston, which is equal to the piston rod area, the piston will extend.As the piston extends, fluid is displaced from the extension volume to176, through the high pressure chamber 178 and the controlled valve 187to the compression chamber 175, simultaneously fluid will flow from thelow pressure chamber into the second port 182 of the IMGU 72decompressing the compressible medium 185 therein.

When the damper is required to be retracted, electrical power issupplied to the motor/generator so that there is fluid flow from thefirst port 181 of the IMGU 72 to the high pressure chamber 178. Thecontrolled valve 187 is held closed and the controlled valve 186 isopened so that the compression chamber 175 is in fluid communicationwith the low pressure chamber 180, bypassing the check valve 183. As thecompression volume 175 is now in fluid communication with the lowpressure chamber 180, a pressure differential across the piston willexist causing the piston to retract. As the piston retracts, fluid willflow from the compression chamber 175 to the low pressure chamber 180and into the second port 182 of the IMGU 72. Because the volume of thecompression chamber 175 is larger than the volume of extension chamber176 by the rod volume, this volume differential will flow from thecompression chamber 175 to the low pressure chamber 180 compressing thecompressible medium 185 therein.

In some embodiments the integrated systems disclosed herein may be usedin conjunction with passive damping, either in parallel with bypassvalves, or in series with the hydraulic motor. Passive valving is wellknown in the art, often incorporating shim stacks, directional valves,and spring-loaded fluid-restrictive porting. Bypass paths may allow foreither lower damping than the viscous losses through the hydraulic motorcan allow, or to tune subtle ride characteristics, however, the presentinvention(s) is not limited in this regard. Series valving may allow forhigher damping than the electric generator can provide in fullsaturation (at very high velocities), a requirement especially importantin heavy duty use scenarios such as military dampers. Parallel or seriesdamping can be incorporated directly on the piston head, in externalbypass tubes, in base valves, or elsewhere.

In some applications the dynamic range required by the damper may bebeyond that which can be reasonably supplied by the hydraulic motor andgenerator. In such applications the integrated systems disclosed hereinmay be used in conjunction with one or more active/controlled valves,either in parallel or in series (or a combination of both) with thehydraulic motor. In one embodiment, one or more active/controlled valvesmay be used separately or in combination with one or more passivevalves. The active/controlled valves may be adapted to operate at apredetermined pressure. The predetermined pressure may be varied toaccording to the operating needs of the damper, hydraulic motor, orgenerator. In addition, the pressure may be selected to dynamicallyincrease or decrease the damping range beyond that which can be suppliedby the hydraulic motor and generator. One or more of theactive/controlled valves may be controlled electrically or by some formof mechanical or hydro-mechanical actuation. In addition, one or moreactive/controlled valves may be adapted to provide a unidirectional flowof fluid. By placing the controlled valves in parallel with thehydraulic motor, flow can be diverted by an externally controllablemeans to bypass the hydraulic motor to lower damping forces by reducingthe viscous losses through the hydraulic motor. By placing thecontrolled valves in series, flow can be restricted either into or outof the hydraulic motor by an externally controllable means to increasethe damping forces beyond which the generator can supply at fullsaturation. These valves can be incorporated directly on the pistonhead, externally in base valves, or elsewhere.

In some embodiments where the device is used as an actuator instead of,or as well as, an energy harvesting damper, additional control valvessuch as load holding valves, pressure limiting valves, etc. may beincorporated to provide different functionality as required by theapplication.

According to some embodiments, a controller may provide a varyingimpedance to the electric generator to control the force response of thedamper based on various parameters such as velocity or position, whilesimultaneously capturing energy associated with movement in the damper.The force response may follow an equation or a lookup table based onsuch parameters. This level of control is called semi-active damping, asthe amount of damping is controlled, but the system is not actuated. Inother use scenarios, the electric motor/generator in the damper can beactuated to allow for fully-active control.

In some embodiments the integrated systems disclosed herein may be usedin an autonomous fashion where the controller bootstraps power from theenergy-harvesting damper. This allows for either a semi-active damper,or in some embodiments, an active damper that generates electricity anduses the electricity to power its own control circuitry. Such a systemmay allow for easy vehicle retrofits with the improved semi-active orfully-active suspensions without the requirement of running wires alongthe vehicle chassis. In one embodiment, a bootstrap capacitor is tied tothe output of the energy generating damper. As the damper generateselectricity, the capacitor is charged. Meanwhile, the controller's powerinput is connected in parallel to this capacitor. As soon the bootstrapcapacitor reaches some voltage to threshold, the controller turns on andbegins controlling the kinematic characteristic on the damper by usingits own generated electricity. Capacitors or a small battery can be usedon the input of the controller to filter transient voltage inputs.

It should be appreciated that in many embodiments, the systems describedherein may be used in conjunction with a spring mechanism to eithercompress or extend the piston rod.

It should be appreciated that for vehicular applications, theembodiments shown can be configured as dampers or as strut type dampersas the applications requires.

What is claimed is: 1-166. (canceled)
 167. A vehicle active suspensionsystem comprising at least two actuators, wherein each actuatorcomprises: a piston disposed in a fluid filled first housing, whereinthe piston divides at least a portion of the housing into a compressionvolume and an extension volume; a second housing containing a hydraulicpump with a first port in fluid communication with the compressionvolume and a second port in fluid communication with the extensionvolume; and an electric motor at least partially located in the pumphousing and operatively coupled to the hydraulic pump; wherein during atleast a first mode of operation the electric motor drives the hydraulicpump to actively drive the piston.